1. Field of the Invention
The present invention relates to a backlight apparatus, more particularly to a technology which improves ease of insertion and replacement of a reflector including a light source in a backlight apparatus.
2. Description of the Prior Art
In recent years, flat panel displays are becoming the mainstream and expanding their market instead of cathode ray tubes which have been conventionally used as display apparatuses. Among others, liquid crystal displays (LCDs) are characterized by their thinness, light weight, low power consumption, and high definition, and have been widely used in the fields of televisions, personal computers and the like.
An LCD display usually comprises: an LCD module composed of an LCD panel—having a pair of mutually facing electrode boards and liquid crystal sealed therebetween—and a polarizing plate; a backlight apparatus which illuminates the LCD module from the rear surface; and various circuit boards which are used to drive the LCD module.
FIG. 5 is an exploded perspective view of a backlight apparatus 1 of the edge type (hereinafter called as a backlight apparatus 1) before a line light source 7 (not shown in FIG. 5) is built in. The backlight apparatus 1 is so constituted that a reflecting sheet 5, an optical sheet 3 and an light guide plate 4 are housed in a housing 2 which is formed by putting a first frame 2a and a second frame 2b together. Here, the optical sheet 3 is a laminate of a diffusing sheet and a light condensing sheet and is disposed on the upper surface of the light guide plate 4, and the reflecting sheet 5 is disposed on the lower surface of the light guide plate 4.
FIG. 6 is a perspective view of the backlight apparatus 1 before a reflector 6 is built in. As shown in FIG. 6, the backlight apparatus 1 houses the light guide plate 4 and various optical sheets 3 (not shown in FIG. 6). The reflector 6, which retains therein the line light source 7, can be inserted from an inserting opening 8 formed through a side wall of the housing 2. The reflector 6 is disposed in a space between a side surface of the optical guide plate 4 and a side wall of the housing 2, and the line light source 7 is disposed in a position to facing the side surface of the light guide plate 4. Besides, the light guide plate 4 and the reflector 6 are sandwiched vertically between a first frame 2a and a second frame 2b to be retained in position (see FIG. 5).
When the backlight apparatus 1 structured as described above is used in an LCD display apparatus, the light emitted from the line light source 7 enters the light guide plate 4 through a side surface thereof, travels throughout the light guide plate 4 by repeating irregular reflection, reflects off the reflecting sheet 5 disposed on the lower surface of the light guide plate 4 in the upward direction and exits from the light guide plate 4 through the upper surface thereof, passes through the optical sheet 3 and illuminates evenly the LCD panel (not shown in FIG. 6).
On the other hand, when the line light source 7 retained inside the reflector 6 is replaced, the line light source 7 is pulled out via the inserting opening 8 together with the reflector 6, and the line light source 7 is replaced. Thus, the reflector 6 only can be removed without disassembling the backlight apparatus 1. After the line light source 7 is replaced, the reflector 6 is inserted via the inserting opening 8 again, and can be built in the housing 2 by being slid into the space between the side surface of the light guide plate 4 and the side wall of the housing 2.
To curb unevenness in the optical properties of the backlight apparatus 1 and make the entire apparatus small and thin, only the space for housing the reflector 6 needs to be formed between the side surface of the light guide plate 4 and the side wall of the housing 2 to reduce an unnecessary clearance.
FIG. 7 is a perspective view of the reflector retaining the line light source 7 therein. As shown in FIG. 7, an upper plate 6a, a side plate 6b and a lower plate 6c of the reflector are put together to have substantially a C-shaped section, house the line light source 7 therein and retain both ends of the line light source 7 with retaining members 9. Besides, an anode and a cathode are connected to leads 10a and 10b respectively at both ends of the line light source 7. The one lead 10a passes along the rear side of the side plate 6b of the reflector 6 and is bundled with the other lead 10b, and electrically connected to their respective inverters.
FIG. 8 is a perspective view of the backlight apparatus 1 after the reflector 6 is built in. As shown in FIG. 8, when the reflector 6 is inserted into the housing 2, the one lead 10b is pulled through the space between the rear surface of the side plate 6b of the reflector 6 and the side wall of the housing 2, and is drawn out via the inserting opening 8.
However, in this structure, although the reflector 6 housed in the housing 2 is vertically sandwiched and retained between the first frame 2a and the second frame 2b, it is not supported tightly thereby in the direction perpendicular to the inserting direction of the reflector 6, because the space through which the lead 10b passes is formed between the side plate 6b and the side wall of the housing 2. Therefore, there has been a problem that the reflector 6 is not securely fixed in the housing 2 and unevenness in the optical properties is caused. Also there has been a disadvantage that if the space between the side plate 6b of the reflector 6 and the side wall of the housing 2 is made small to make the lead 10b support tightly the side plate 6b of the reflector 6, the lead 10b can be damaged and the efficiency of insertion and replacement of the reflector can be lowered.
Accordingly, conventionally, to solve the problems, in JP-A-H11-134921, for example, a predetermined clearance is formed between the side wall of the housing and the reflector, and a lamp cover is disposed over the rear surface of the side plate of the reflector to protect the lead.
However, according to the invention described in JP-A-H11-134921, because the lamp cover needs to be disposed between the side wall of the housing and the reflector, the backlight apparatus cannot be made compact and the insertion of the reflector cannot be carried out efficiently.